Problem: What is the volume of a cylinder with base radius $3$ and height $7$ ? $3$ $7$
The area of the base is simply the area of a circle: $\pi r^2 = \pi \cdot 3^2 = 9 \pi$ The volume of the cylinder is the area of the base times the height: $B \cdot h = 9\pi \cdot 7 = 63\pi$.